A semiconductor device with a novel structure is provided in which stored data can be held even when power is not supplied and the number of writing is not limited. The semiconductor includes a second transistor and a capacitor over a first transistor. The capacitor includes a source or drain electrode and a gate insulating layer of the second transistor and a capacitor electrode over an insulating layer which covers the second transistor. The gate electrode of the second transistor and the capacitor electrode overlap at least partly with each other with the insulating layer interposed therebetween. By forming the gate electrode of the second transistor and the capacitor electrode using different layers, an integration degree of the semiconductor device can be improved.